1. Field of the Invention
The present invention relates to an information processing apparatus in which a data recording disc, such as an optical disc, is accommodated. Particularly, it relates to a mechanism for unloading a disc loaded on a turntable.
2. Description of the Related Art
Optical disc apparatus which employ an optical disc as a data storage medium have made possible a large increase in storage capacity compared with previously used magnetic disc loading apparatus. The optical disc apparatus can reproduce data in a stable manner with minimal noise. Further, in such an apparatus, extremely stable reproducing conditions are obtained, which are substantially unaffected by external influences. Moreover, since the data processing is performed without physical contact between a recording/reproducing head and the surface of the optical disc, damage of the optical head and the optical disc are minimized. Therefore, the use of such optical disc apparatus has increased greatly.
In a conventional cartridge loading apparatus, as shown in U.S. Pat. No. 4,439,850 (Takahara et al), in order to hold the disc accommodated in the cartridge on a turntable, it is pressed against the turntable from the opposite side thereof, by means of a clamper. The clamper receives a clamping force from urging means by magnetic attraction produced between the clamper and turntable. In this construction, the clamper is formed of magnetic material, and the turntable has a magnet therein. The conventional apparatus requires a space for accommodating the clamper. Further, a drive mechanism is necessary for moving the clamper toward or away from the optical disc. As a result, the apparatus is bulky and complicated to construct and inevitably is larger, heavier and more expensive to produce. Also, the use of the clamp mechanism makes it difficult to assemble the apparatus and to maintain it in proper alignment.
An invention of the same assignee is disclosed in a related U.S. application, Ser. No. 004,097 filed Jan. 16, l987, which disclosure is hereby incorporated by reference herein. It is believed that this disclosure does not constitute prior art with respect to the present invention. This related application describes an information processing apparatus including an optical disc and a drive mechanism for rotating the disc. The disc comprises a disc-shaped body with an attractable portion at the central portion of the body. The attractable portion has an attractable member projecting from the body. A center hole, defining the center of rotation of the body, is cut in the attractable member. The drive mechanism includes a turntable which is rotated by a motor. A depression is formed in a support surface of the turntable. A magnetic attraction unit is arranged in the depression so as to magnetically attract the attractable portion, whereby the attractable member is housed in the depression and the surface of the body is contact with the support surface. Thus, the disc can be mounted stably on the turntable, irrespective of the thickness of the disc, and without the need for clamp mechanism, which has conventionally been used. Such clamp mechanisms have prevented reduction in size, weight, and costs of manufacturing the apparatus.
In an apparatus of this type, where the disc is held by magnetic attraction, the mounted condition of the disc maybe released by directly lifting the disc in the perpendicular direction. However, when the mounted condition is released in this way, since the surface of the disc and the support surface of the turntable are always parallel, a large force is required to counter act the magnetic attraction and release this mounted condition of the disc. This means that a larger motor maybe required for the apparatus, or greater power must be needed to overcome the magnetic force.